On my 87 300e, I noticed the number 1 printed, i think in yellow, on the front strut's black housing, near the lower bolt. I saw a picture of another solid black strut with the number 5. What do these numbers mean. I do not know the brand of either strut. Thanks.

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87 300e (white/black; amg body kit)
88 300ce (red/cream; amg body kit)
93 300ce cabrio (white/blue/blue top)
93 300ce cabrio (black/grey/black top)
98 ml 320 (totaled @ 137,000 miles)
99 clk320 (black/grey/black top)